From: Dan Nelson
Date: August 28 2002 3:10pm
Subject: Re: MySQL/InnoDB-4.0.3 is released
List-Archive: http://lists.mysql.com/mysql/118227
Message-Id: <20020828151013.GA12910@dan.emsphone.com>
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In the last episode (Aug 28), Harald Fuchs said:
> I think there's something missing in the changelog. About a month
> ago, someone named Christian Jaeger from ETH Zurich asked about
> unbuffered raw device support for Linux. You replied immediately
> with two sets of patches for 3.23.x (regaring unaligned access) which
> apparently fixed the problems, for Mr. Jaeger at least. When I tried
> to apply those patches to 4.0.2, I still got operating system error
> #22. Thus I decided to wait for 4.0.3.
On a similar topic, many OSes support "Direct I/O" on files, which
causes reads and writes to bypass the system's buffer cache. It's
usually enabled by adding the O_DIRECT (or O_DIRECTIO) flag to your
open() call. From a quick Google search, FreeBSD and IRIX use
O_DIRECT, Tru64 uses O_DIRECTIO, and Solaris has you call a directio()
function on the file descriptor after you open the file.
Adding this should really help performance on large InnoDB tablespaces,
and keeps you from having to fall back to raw partitions for unbuffered
IO, which are a pain to manage.
--
Dan Sql Query Nelson
dnelson@stripped